High mortality rates of Angora goats during periodic cold climatic spells cause considerable annual monetary loss in the mohair industry. Angora goats are most susceptible to cold spells during the first few weeks after shearing. Various measures have been taken in the past to prevent losses during cold spells, with varying success rates. Some Angora goat producers also made use of coats for protection against the elements. However, no information is available on the effect of coats on hair quality traits of South African Angora goats.

A request was made by the mohair industry to Grootfontein Agricultural Development Institute (GADI) to investigate the suitability of coats as protection against adverse weather conditions. Mohair South Africa furthermore requested GADI to extend the project to include the evaluation of hair quality traits of treated animals. The aim of this project was therefore to determine the effect of protective coats on hair quality traits of Angora goats.

MATERIAL AND METHODS

The study was conducted at the Grootfontein Agricultural Development Institute under kraal and veld conditions. Forty-eight ten-month-old castrated male Angora goat kids from the Grootfontein Angora herd were used for the study.

All animals were shorn during the first week of August 2009. The animals were weighed and then divided into two groups on a stratified body weight basis. The first group of 24 animals received no protective body covering (Control group), while the second group received protective coats (Coats group) on the day after shearing.

The coats used in this trial were the Bisa sheep coats. These were made of a new material, consisting of Nylon 6, which has been developed to overcome some of the problems encountered with previous designs. This material will prevent contamination of the fleece. It is also Teflon-treated to make it water-resistant, as well as electrostatically treated against bacterial and fungal infestation.

Style and character were assessed on a linear scale from 1 to 50 (Table 1) at two months and six months after shearing. A midside fleece sample was taken for fibre diameter, clean yield and staple length determination from each goat at six months after shearing.

At two months after shearing, the coats of half of the Coats group were removed. At four months after shearing, the remaining coats were replaced with bigger coats, as the coats were getting too small for the animals.

Table 1. Linear scale for the assessment of hair quality traits

Trait

Scale

1

25

50

Style

No style

Average style

Excellent style

Character

Straight

Ideal

Over curly

The SAS statistical package (PROC GLM) was used to determine differences in hair quality traits of goats that received protective coats and those without any protection (SAS, 2006).

The following model was applied for all hair traits:

Yij = µ + ti + b1BW + b2SC + eij

Where

Yij = trait of the j'th animal of the i’th treatment group,

µ = overall mean,

ti = fixed effect of the i'th treatment group (Coats for six months, Control, Coats for two months),

b1 = linear regression coefficient of the appropriate deviation from the mean of body weight at the start of the trial (BW),

b2 = linear regression coefficient of the appropriate deviation from the mean of style/character assessed at two months’ hair growth (SC; fitted for six month traits),

eij = random error with zero mean and variance Is2e.

RESULTS

Three of the smaller animals lost their coats during the first week of the trial (the coats were replaced the same day or early the next morning). None of the coats got torn, however, the goats were not kept in very thorny veld. They were run in camps with saltbush, grass and smaller shrubs. Hair quality assessments are summarised in Tables 2 and 3.

Table 2. Assessment of style over the experimental period

Coats

Control

Coats removed after two months

Two months after treatment

22.21 ± 1.48

19.56 ± 1.45

Six months after treatment

17.62ab ± 1.52

25.42a ± 1.03

23.91b ± 1.11

a,b Values with the same superscripts differed significantly (P<0.05)

No significant differences were observed in assessed style score two months after treatments were applied. However, at six months’ hair growth (six months after application of treatments) those animals that had the coats on for the entire six-month period had poorer style than the Control group and those animals that wore the coats for a two-month period. The latter animals had similar style as the Control group animals.

Table 3. Assessment of character over the experimental period

Coats

Control

Coats removed after two months

Two months after treatment

25.67 ± 1.49

22.00 ± 1.46

Six months after treatment

29.07ab ± 0.86

23.65a ± 0.57

25.00b ± 0.81

a,b Values with the same superscripts differed significantly (P<0.05)

No significant differences were observed in assessed character score two months after treatments were applied. At six months’ hair growth those animals that had the coats on for the entire six-month period had the best character score (P<0.05). The scores assessed for the other groups did not differ significantly.

Clean yield, staple length and fibre diameter of the fleeces six months after treatment are summarised in Table 4. Again, those animals that had the coats on for the entire six-month period had the best clean yield percentage (P<0.05). No significant differences were observed for staple length among the treatment groups. Those animals that had the coats on for the entire six-month period had the highest fibre diameter (P<0.05).

In a study with Angora goats in Texas (Lupton et al., 2008), it was found that the coated goats produced fleeces with higher clean yields (74% versus 71%) compared to those from uncoated animals. Coats, however, did not affect any of the other measured hair quality traits.

Coats significantly reduced wool dust content, suint content and vegetable matter contamination of western Australian Merino wool, leading to improved wool yields (Campbell & Schlink, 2007). Fibre diameter, staple length, staple strength and clean fleece weight were not significantly influenced by the use of coats. Hatcher et al. (2003, 2008) found similar results, where the major effect of the sheep coats was to improve the style of the wool. This was largely the result of the coated fleeces being whiter, with less tip weathering and lower levels of dust and vegetable matter. There was also no significant difference between treatment groups in wool production, fibre diameter or staple strength. Similar results where sheep coats were successful in reducing the dust and vegetable matter contamination and improving some quality traits of Australian and Chinese wools were reported by Ford & Cottle (1993), Davies et al. (1994) and Crowe et al. (1996).

As far as the hair quality is concerned, animals that wore the coats for a six-month period had better character of their hair and the best clean yield, but they also had the worst style and the highest fibre diameter. When the coats are worn for only a two-month period, no important differences among hair quality traits were observed between the Coat and Control group animals.

When exposed to cold conditions, the body loses heat through the skin at a more rapid rate than under higher ambient temperature conditions (McCullough & Arora, 2004). This increased heat loss causes the hypothalamus to activate the temperature regulation mechanisms (Kaiser, 2010). One of these is that the blood vessels in the skin constrict to prevent excessive heat loss. Significantly higher skin temperatures were recorded on the shoulder and britch of Coats than Control group animals (Snyman & Van Heerden, 2011). This is the area directly covered by the coats. This higher temperature indicates a higher blood flow to the skin, with a resultant higher supply of nutrients, which could explain the higher fibre diameter of Coats group animals that wore the coats for a six-month period.

CONCLUSIONS

From the results obtained with the current study, it is obvious that protective coats will have no detrimental effect on hair quality traits when the coats are worn for a two-month period after shearing. It is not recommended to wear the coats for the entire six-month period, due to the resultant poorer style and higher fibre diameter, although coated fleeces had better character and a higher clean yield than unprotected fleeces.

ACKNOWLEDGEMENTS

Mohair South Africa is acknowledged for funding of the project.

REFERENCES

Campbell, I.R.D. & Schlink, A.C., 2007. Efficacy of sheep coats for part of the year in western Australian Merino flocks. Anim. Prod. Austr. 25, 29-32.